Secrets of the Soil

Farmers know fertility is critical for success. But beyond the "big three nutrients" of N, P and K, not nearly as much time and resources are invested to learn more about so-called secondary nutrients.

USDA researchers, university scientists, consultants and others met in Indiana Aug. 21 to share their findings and practical insights about two lesser-understood nutrients, calcium and sulfur. More than 150 people were on hand to learn more about gypsum, a mineral that delivers both calcium and sulfur, at the Midwest Soil Improvement Symposium (MSIS), held at the Rulon family farm in Arcadia, Ind. The event was sponsored by Rulon Enterprises, Gypsoil and the Conservation Technology Information Center.

Gypsum is a soft mineral that is composed of calcium sulfate dehydrate, which breaks down into calcium and sulfur over time. Farmers around the world have used it for centuries (Benjamin Franklin was a proponent in colonial times, for example), but gypsum has largely evaded modern research. The researchers presenting at MSIS have championed the efforts to learn more about gypsum, even when it was not popular to do so.

"People used to tell me I was wasting my time," says Warren Dick, professor at The Ohio State University’s school of environment and natural resources. "But now there’s all sorts of interest in gypsum."

Dick wrote the book on gypsum – literally. He is the co-author of a leading publication on the topic, Gypsum as an Agricultural Amendment. Dick and other researchers have studied gypsum’s benefits not only to crops like corn and soybeans, but also to the soil itself. Retired USDA soil scientist Darrell Norton, for example, spent several decades studying evaluating how gypsum affected soil and water quality, particularly as a runoff management tool.

Ongoing research confirms that gypsum can improve crusting and erosion by allowing the soil structure to filtrate water better. Recent USDA studies showed adding gypsum could reduce the rate of contaminate phosphorous in water runoff by as much as 34%.

Norton says he is worried that future regulations could create a scenario where "it could be illegal for nutrients to leave your farm." Still, he says, there is tremendous upside for farmers who invest in improving soil health on their farm through a variety of practices, including gypsum usage, cover crops, conservation tillage practices and more.

"As you increase soil quality, someday the value of those fields is going to increase greatly," he says.

Joe Nester, an Ohio-based consultant who participated in one of the MSIS panels, agreed that looking into different ways to improve soil health is a smart investment.

"There’s going to come a time when soil health will be measurable and it will affect land values," he says. "Soils aren’t all created equal."

In the video below, Dick lays out a quick timeline of agricultural interactions with gypsum through the ages.